Britain's monthly exports to China have hit the £1bn level for the first time amid signs that UK firms are diversifying away from the crisis-hit eurozone.

The Office for National Statistics said there had been a marked shift in Britain's trading patterns over the past 18 months as it revealed that the country's trade gap narrowed by £600m in April.

Latest data showed that the trade gap in April fell from £3.2bn to £2.6bn as imports fell more sharply than exports. An £8.2bn deficit in goods was partly offset by a £5.6bn surplus in trade in services.

Both imports and exports fell in April, but the 2.7% decline in the value of imports outstripped the 1.3% drop in exports.

Over the three months to April – considered a better guide to the underlying trend by the ONS – the deficit in goods and services widened by £500m to £9bn.

Since the second half of 2011, exports to the EU have fallen by 5% while those to the rest of the world have risen by 7%. In the quarter ending in April, exports to China were up by 11% and averaged more than £1bn a month.

Even so, the trade gap with China deteriorated since the £300m increase in exports in the quarter ending in April was accompanied by a £500m increase in imports.

Britain's trading position with the US improved, with a 7% rise in exports and a fall in imports creating a quarterly surplus of £3.7bn.

But the deficit with Germany widened markedly. Exports to the UK's second-biggest market after the US fell by £800m to £7.5bn while imports were up £200m to £13.5bn.

"There has been a switch in the trade with EU countries and the rest of the world since the autumn of 2011," the ONS said. "In that period, the deficit with the non-EU countries averaged around £15bn over a three-month period; the deficit with the rest of the EU was around £11bn. The positions are now reversed."

Howard Archer, chief UK economist at IHS Global Insight, said: "Overall, it is clear that UK exports are continuing to struggle despite the marked weakening of the pound earlier this year. Obviously, muted and stuttering global growth is a problem, especially persistent weak domestic demand in the eurozone. Nevertheless, the export performance is still disappointing."